diff --git a/thread.c b/thread.c
index ed771166e6..2d3a3e15c2 100644
--- a/thread.c
+++ b/thread.c
@@ -4242,6 +4242,9 @@ sigwait_timeout(rb_thread_t *th, int sigwait_fd, const rb_hrtime_t *orig,
     return orig;
 }
 
+#define sigwait_signals_fd(result, cond, sigwait_fd) \
+    (result > 0 && (cond) ? (result--, (sigwait_fd)) : -1)
+
 static VALUE
 do_select(VALUE p)
 {
@@ -4277,13 +4280,10 @@ do_select(VALUE p)
 	}, set->sigwait_fd >= 0 ? ubf_sigwait : ubf_select, set->th, TRUE);
 
         if (set->sigwait_fd >= 0) {
-            if (result > 0 && rb_fd_isset(set->sigwait_fd, set->rset)) {
-                result--;
-                (void)check_signals_nogvl(set->th, set->sigwait_fd);
-            }
-            else {
-                (void)check_signals_nogvl(set->th, -1);
-            }
+            int fd = sigwait_signals_fd(result,
+                                        rb_fd_isset(set->sigwait_fd, set->rset),
+                                        set->sigwait_fd);
+            (void)check_signals_nogvl(set->th, fd);
         }
 
         RUBY_VM_CHECK_INTS_BLOCKING(set->th->ec); /* may raise */
@@ -4430,12 +4430,8 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
             }, ubf, wfd.th, TRUE);
 
             if (fds[1].fd >= 0) {
-                if (result > 0 && fds[1].revents) {
-                    result--;
-                    (void)check_signals_nogvl(wfd.th, fds[1].fd);
-                } else {
-                    (void)check_signals_nogvl(wfd.th, -1);
-                }
+                int fd1 = sigwait_signals_fd(result, fds[1].revents, fds[1].fd);
+                (void)check_signals_nogvl(wfd.th, fd1);
                 rb_sigwait_fd_put(wfd.th, fds[1].fd);
                 rb_sigwait_fd_migrate(wfd.th->vm);
             }